Optical imaging systems are widely used for reading coded patterns on packages or articles. One of the most common of these is the bar code reader. Such a device can be a portable handheld device or a fixed mount device mounted along a conveyor for packages or articles. As with other imaging devices, results are improved if the device is the proper distance from the article to be scanned or read, so that the image is “in focus.”
Known prior optical decoding systems have used a crosshair-type illumination to properly aim a handheld reader at an object to be read, as disclosed in Feng, U.S. Pat. No. 5,783,811. Swartz et al., U.S. Pat. No. 5,734,153, disclosed that an aiming beam could provide one or more illuminated spots or a line on the target area. Roustei, U.S. Pat. No. 6,347,163, disclosed splitting an aiming beam into two generally parallel beamlets for framing the sides of a field of view. Beams that have been used for determining a focus distance have generally used a triangulation method involving intersection of the two beams or some other intersection method.
It is desired to provide a new and improved focusing system to signal a user that the target area is in focus and that the imaging data being read is good data.
None of these references provide or suggest the solution which is the subject of the present invention.